One component supplier, Avnet Inc, stopped working with Apple because the relationship was squeezing its profit margins too much.

Apple has developed its own processors for years, but has in recent years stepped up in-house design of components, including graphics, Bluetooth and other smartphone-related chips. That is expensive and creates new risks, but it helps the company maintain leverage over suppliers as a recent wave of acquisitions cut the number of chipmakers it works with.

To secure cheaper prices, Apple likes to have at least two suppliers for any given component. However, last year alone, one in five US chipmakers were acquired, Susquehanna Financial Group data showed.

This year is particularly important for Apple, because it is preparing to launch three iPhones, including a flagship device with a major new design. The installation of new manufacturing lines and processes is costly, so Apple needs to find savings elsewhere.

Apple was last year in acquisition talks with Imagination Technologies. The Kings Langley, England-based company designs a type of chip called a graphics processing unit that has been used in iPhones and iPads, and analysts theorized Apple wanted to take the technology in house and push it forward on its own terms.

Apple decided against making an offer.

On April 3, Imagination said Apple would stop using its graphics technology after developing its own solutions.

The British company lost about two-thirds of its market value that day.

In the past five years, Apple doubled research and development spending as a percentage of revenue, an increase chief financial officer Luca Maestri attributed to new product categories and developing more of its own underlying technology, among other factors.

Semiconductor research is among the most expensive in the technology industry, often exceeding 18 percent of revenue. Apple spends 4.7 percent of its income on research and development, up from 2.2 percent in 2012.

Meanwhile, tapering growth of smartphone sales has heightened the need to squeeze every last dollar of profit out of the handsets that Apple does sell.

The main risk is that Apple misses new technology trends that bubble up through a large supply chain. Relying more on internally created components, it will have fewer suppliers lining up to show it the latest innovations.

Then there is the risk that some partners decide they do not want to deal with Apple anymore.